[Paleopsych] SW: Social Hierarchy and Primate Health
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Sociobiology: Social Hierarchy and Primate Health
http://scienceweek.com/2005/sw050701-5.htm
The following points are made by Robert M. Sapolsky (Science 2005
308:648):
1) One of the greatest challenges in public health is to understand
the "socioeconomic gradient." This refers to the fact that in numerous
Westernized societies, stepwise descent in socioeconomic status (SES)
predicts increased risks of cardiovascular, respiratory, rheumatoid,
and psychiatric diseases; low birth weight; infant mortality; and
mortality from all causes [1-4]. This relation is predominately due to
the influence of SES on health, rather than the converse, and the
disease incidences can be several times greater at the lower extreme
of the SES spectrum.
2) One set of questions raised by the gradient concern its external
causes. Despite human aversion to inequity in some settings [5], many
Westernized societies tolerate marked SES gradients in health care
access. Is this the predominant cause of the health gradient, or is it
more a function of differences in lifestyle risk factors or of the
psychosocial milieu in which poverty occurs?
3) Another set of questions concern the physiological mediators of the
SES-health relationship -- how, in a frequently used phrase in the
field, does poverty get under the skin? These physiological questions
are difficult to study in humans, and an extensive literature has
focused instead on nonhuman animals. Despite the demonstration that
some nonhuman species can also be averse to inequity, groups of social
animals often form dominance hierarchies, producing marked
inequalities in access to resources. In such cases, an animal's
dominance rank can dramatically influence the quality of its life.
Does rank also influence the health of an animal?
4) The study of rank-health relations in animals has often been framed
in the context of stress and the idea that animals of different ranks
experience different patterns of stress. A physical stressor is an
external challenge to homeostasis. A psychosocial stressor is the
anticipation, justified or not, that a challenge to homeostasis looms.
Psychosocial stressors typically engender feelings of lack of control
and predictability and a sense of lacking outlets for the frustration
caused by the stressor. Both types of stressor activate an array of
endocrine and neural adaptations. When mobilized in response to an
acute physical challenge to homeostasis (such as fleeing a predator),
the stress response is adaptive, mobilizing energy to exercising
muscle, increasing cardiovascular tone to facilitate the delivery of
such energy, and inhibiting unessential anabolism, such as growth,
repair, digestion, and reproduction. Chronic activation of the stress
response by chronic psychosocial stressors (such as constant close
proximity to an anxiety-provoking member of one's own species) can
increase the risk of numerous diseases or exacerbate such preexisting
diseases as hypertension, atherosclerosis, insulin-resistant diabetes,
immune suppression, reproductive impairments, and affective disorders.
5) In summary: Dominance hierarchies occur in numerous social species,
and rank within them can greatly influence the quality of life of an
animal. The author considers how rank can also influence physiology
and health. The author first considers whether it is high- or
low-ranking animals that are most stressed in a dominance hierarchy;
this turns out to vary as a function of the social organization in
different species and populations. The author then reviews how the
stressful characteristics of social rank have adverse adrenocortical,
cardiovascular, reproductive, immunological, and neurobiological
consequences. Finally, the author considers how these findings apply
to the human realm of health, disease, and socioeconomic status.
References (abridged):
1. N. Adler et al., Health Psychol. 19, 586 (2000)
2. I. Kawachi, B. Kennedy, The Health of Nations: Why Inequality Is
Harmful to Your Health (New Press, New York, 2002)
3. J. Siegrist, M. Marmot, Soc. Sci. Med. 58, 1463 (2004)
4. R. Wilkinson, Mind the Gap: Hierarchies, Health, and Human
Evolution (Weidenfeld and Nicolson, London, 2000)
5. E. Fehr, B. Rockenbach, Curr. Opin. Neurobiol. 14, 784 (2004)
Science http://www.sciencemag.org
--------------------------------
Related Material:
PUBLIC HEALTH: CLASS AND NATIONAL HEALTH
The following points are made by S.L. Isaacs and S.A. Schroeder (New
Engl. J. Med. 2004 351:1137):
1) The health of the American public has never been better. Infectious
diseases that caused terror in families less than 100 years ago are
now largely under control. With the important exception of AIDS and
occasional outbreaks of new diseases such as the severe acute
respiratory syndrome (SARS) or of old ones such as tuberculosis,
infectious diseases no longer constitute much of a public health
threat. Mortality rates from heart disease and stroke -- two of the
nation's three major killers --have plummeted.(1)
2) But any celebration of these victories must be tempered by the
realization that these gains are not shared fairly by all members of
our society. People in upper classes -- those who have a good
education, hold high-paying jobs, and live in comfortable
neighborhoods -- live longer and healthier lives than do people in
lower classes, many of whom are black or members of ethnic minorities.
And the gap is widening.
3) A great deal of attention is being given to racial and ethnic
disparities in health care.(2-5) At the same time, the wide
differences in health between the haves and the have-nots are largely
ignored. Race and class are both independently associated with health
status, although it is often difficult to disentangle the individual
effects of the two factors.
4) The authors contend that increased attention should be given to the
reality of class and its effect on the nation's health. Clearly, to
bring about a fair and just society, every effort should be made to
eliminate prejudice, racism, and discrimination. In terms of health,
however, differences in rates of premature death, illness, and
disability are closely tied to socioeconomic status. Concentrating
mainly on race as a way of eliminating these problems downplays the
importance of socioeconomic status on health.
5) The focus on reducing racial inequality is understandable since
this disparity, the result of a long history of racism and
discrimination, is patently unfair. Because of the nation's history
and heritage, Americans are acutely conscious of race. In contrast,
class disparities draw little attention, perhaps because they are seen
as an inevitable consequence of market forces or the fact that life is
unfair. As a nation, we are uncomfortable with the concept of class.
Americans like to believe that they live in a society with such
potential for upward mobility that every citizen's socioeconomic
status is fluid. The concept of class smacks of Marxism and economic
warfare. Moreover, class is difficult to define. There are many ways
of measuring it, the most widely accepted being in terms of income,
wealth, education, and employment.
6) Although there are far fewer data on class than on race, what data
exist show a consistent inverse and stepwise relationship between
class and premature death. On the whole, people in lower classes die
earlier than do people at higher socioeconomic levels, a pattern that
holds true in a progressive fashion from the poorest to the richest.
At the extremes, people who were earning $15,000 or less per year from
1972 to 1989 (in 1993 dollars) were three times as likely to die
prematurely as were people earning more than $70,000 per year. The
same pattern exists whether one looks at education or occupation. With
few exceptions, health status is also associated with class.
References (abridged):
1. Institute of Medicine. The future of the public's health in the
21st century. Washington, D.C.: National Academies Press, 2003:20.
2. Smedley BD, Stith AY, Nelson AR, eds. Unequal treatment:
confronting racial and ethnic disparities in health care. Washington,
D.C.: National Academy Press, 2003
3. Steinbrook R. Disparities in health care -- from politics to
policy. N Engl J Med 2004;350:1486-1488
4. Burchard EG, Ziv E, Coyle N, et al. The importance of race and
ethnic background in biomedical research and clinical practice. N Engl
J Med 2003;348:1170-1175
5. Winslow R. Aetna is collecting racial data to monitor medical
disparities. Wall Street Journal. March 5, 2003:A1
New Engl. J. Med. http://www.nejm.org
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